One of the recent trends in designing automotive vehicles is to equip an automotive vehicle with various extra instruments and accessories which have thus far been offered for users' option. Typical examples of these instruments and accessories are audio players and drive computers (which are the instruments to display the fuel consumption rates and the scheduled times of arrival at the destinations of travel). Such instruments and accessories are sometimes required to have been incorporated in completed automotive vehicles before the vehicles are delivered "ex factory."
Provision of the additional instruments and accessories has enhanced the centralization of the fitting and wiring arrangements on the instrument panel of an automotive vehicle. Situations presently encountered as a consequence are such that there are practically no spaces available underneath the instrument panel, making more strict the design considerations for the layout of the additional instruments and accessories.
Attempts have therefore been made to install some extra instruments and accessories on a support structure provided inside the rim portion of the steering wheel structure so as to ease the space requirement for the setup of the instruments and accessories.
A known steering mechanism to realize such a scheme comprises a steering main shaft connected to the steering gear mechanism and a steering countershaft arranged in parallel with the main shaft and supporting the steering wheel structure. The main and countershaft are engaged with each other by means of gears respectively mounted or formed on the shafts so that a turning load applied to the steering wheel structure is transmitted to the steering main shaft through the countershaft and the gears which are in mesh with each other. The support structure having mounted thereon an accessory implement such as the switch unit of a warning horn system is supported by a member secured to a steering column tube fixed with respect to the body structure of the vehicle. The countershaft carrying the steering wheel structure is rotatably mounted on such a member and is permitted to turn with the steering wheel structure independently of the switch support structure. Thus, the switch support structure is maintained at a standstill irrespective of the turning motions of the steering wheel structure.
Drawbacks are, however, concomitant with a prior-art steering mechanism of this nature principally due to the intricate construction of the mechanism using the two parallel shafts and the gears respectively mounted or formed on the shafts.
The present invention contemplates provision of a steering mechanism which is free from such drawbacks but which is nevertheless capable of achieving the advantage of the known steering mechanism of the described general nature.